Help with IR LED, too dim, low current - Raspberry Pi Forums
i haven't done breadboarding since college (just after electricity discovered), may dumb problem, i'm going in circles , appreciate advice.
making pi remote control device led on aquarium. used radio shack ir emitter (276-142), , had working great. however, had wired incorrectly, no resistors in play pull down or current limiting. working wanted go through steps of doing "right" , calculations proper resistors.
pulled apart, did thought right calculations (hard find for-sure info on led), put -- didn't work. well, except did work... way dim (with extreme measures pointed directly @ receiver works now).
put old way -- , still doesn't work. did blow something?
replaced transistor - same.
replaced ir led red led, , looks nice , bright (clearly can't tell if works).
more -- hooked +5 ground, ir led draw 5ma. rating says 150ma (again, bit questionable lots of postings radio shack has them labeled wrongly, i've put specs on attachment beside it).
red led (with resistors in place) draws 35ma in same configuration ir led draws 5ma.
base voltage on transistor 0.8v, i've run way 3.3v without change; current draw base emitter 5ma around 15ma, ir led current draw against collector 5ma.
have somehow damaged it, perhaps shorted while rearranging? next step go ir led (i had one), thought post sanity check, see if i'm doing correctly.
10k pull down in case gpio 22 output switched, 500 ohm current limit base protect transistor , should give .8v base, 68 ohm (actually 100+220) current limit flow through transistor , led, again have shorted across , current flow not change.
note while doing ir remote this, when give current , voltage flows that's using webiopi steady state on/off, not pulsed ir control.
advice welcomed, "go college", though i'd prefer more specific.
making pi remote control device led on aquarium. used radio shack ir emitter (276-142), , had working great. however, had wired incorrectly, no resistors in play pull down or current limiting. working wanted go through steps of doing "right" , calculations proper resistors.
pulled apart, did thought right calculations (hard find for-sure info on led), put -- didn't work. well, except did work... way dim (with extreme measures pointed directly @ receiver works now).
put old way -- , still doesn't work. did blow something?
replaced transistor - same.
replaced ir led red led, , looks nice , bright (clearly can't tell if works).
more -- hooked +5 ground, ir led draw 5ma. rating says 150ma (again, bit questionable lots of postings radio shack has them labeled wrongly, i've put specs on attachment beside it).
red led (with resistors in place) draws 35ma in same configuration ir led draws 5ma.
base voltage on transistor 0.8v, i've run way 3.3v without change; current draw base emitter 5ma around 15ma, ir led current draw against collector 5ma.
have somehow damaged it, perhaps shorted while rearranging? next step go ir led (i had one), thought post sanity check, see if i'm doing correctly.
10k pull down in case gpio 22 output switched, 500 ohm current limit base protect transistor , should give .8v base, 68 ohm (actually 100+220) current limit flow through transistor , led, again have shorted across , current flow not change.
note while doing ir remote this, when give current , voltage flows that's using webiopi steady state on/off, not pulsed ir control.
advice welcomed, "go college", though i'd prefer more specific.
hi,
have included voltage drop on leds (ir ones typically higher visible leds) within experiments/calculations ?
best wishes, ivan zilic.
have included voltage drop on leds (ir ones typically higher visible leds) within experiments/calculations ?
best wishes, ivan zilic.
raspberrypi
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